[aidenn0]

SMTP no longer reliably delivers messages. Try setting up an MTA on a Hetzner VPS and see how many messages get through

[vidarh]

That is only relevant if you require delivery to arbitrary endpoints rather than to endpoints explicitly set up to process your messages.

[mrtesthah]

That's not an applicable criticism for SMTP running on a private network and/or dedicated set of "mail" submitting servers, as in the specific model outlined in the grandparent comment.